Bug#627488: No problem when using the businesscard.iso

["H.A.J. Koster" <haj.koster@ziggo.nl>]

Ran into the same problem with the debian-testing-amd64-netinst.iso. 
Specifically, the installer screen goes red when trying to install the 
busybox package, the log shows indeed that it cannot find the source 
image, while it is still mounted. I should add that I am installing in a 
VM from a downloaded .iso file -- tried both a Parallels VM and a 
VirtualBox VM, same problem in either one of them.

I then switched to the debian-testing-amd64-businesscard.iso, and now 
the installation proceeded flawlessly on both VMs (although the 
Parallels Tools don't yet work and produce a black screen and numerous 
Xorg error messages -- but that's another story).